In anatomy, a nerve is a fine long structure capable of being visibly observed, and histologically, is composed of a plurality of nerve bundles. Meanwhile, a nerve bundle is a collection of a plurality of nerve fibers. A nerve fiber denotes a portion of an axon in a nerve cell, and is known as a nerve fiber because the axon has a fine long fibrous shape. Various terms such as axon are used to refer to a nerve fiber.
All nerve fibers are surrounded by endoneurium, a soft connective tissue, nerve bundles are surrounded by perineurium, and nerves, which are bundles of nerve bundles, are surrounded by epineurium. All these membranes are provided to protect nerves, and only the epineurium is distinguishable with the naked eye.
In general, muscles of a human body operate according to electrical stimuli provided from nerves. Accordingly, when abnormality of facial muscles occurs, treatment of nerves connected to the corresponding muscles may be needed
When abnormality of facial nerves or laryngeal nerves occurs, treatments such as drugs, surgery, or the like are performed. In this case, patients receive local massages of corresponding parts in order to stimulate damaged muscles by stimuli to peripheral nerves during recovery of damaged nerves, preventing atrophy of the muscles.
That is, when stimuli to the muscles are obstructed due to surgery, or the like of patients with facial or laryngeal nerve paralytics, since the corresponding muscles may be damaged, causing permanent muscle damage or paralysis, methods of massaging muscles related to the corresponding nerve system or providing electrical stimuli from the outside, or the like have been proposed.
Meanwhile, a conventional device configured to be inserted into a human body to provide a physical stimulus or obtain information of a certain numerical value in the human body has been proposed, and conventional devices are described as follows, which include electrodes providing or detecting electrical stimuli for nerves.
First, a device detecting electric signals of nerves based on a metal-oxide-semiconductor field effect transistor (MOSFET) has been conventionally proposed. This related art is a technique monitoring change of membrane capacitance depending on exterior stimuli using gatings of a MOSFET device, and is a technique of simultaneously monitoring various neural responses. This related art has been applied to a method of detecting nerve signals by fixing positions of snail neurons around a P-MOSFET with picket fences made of polyimide and culturing them with limited mobility (Zeck et. al., Noninvasive neuroelectric interfacing with synaptically connected snail neurons immobilized on a semiconductor chip, Proc Nat Acad Sci 2001; 98).
Second, a technique for detecting electric stimuli of brain stems or nerve fibers has been proposed. Since 2000, the Normann group at University of Utah (USA) and Cyberkinetics have been conducting research on measuring electric signals and stimulating nerves by directly inserting multiple electrodes in nerves and brains (Normann et. al., Long-Term Stimulation and Recording With a Penetrating Microelectrode Array in Cat Sciatic Nerve, IEEE Transactions on Biomedical Engineering, VOL. 51, NO. 1, JANUARY 2004).
Third, a technique of inserting sieve electrodes in nerve fibers has been proposed. Through joint research of Fraunhofer-IBMT (Germany), IMTEK (Germany) and others, regeneration of nerves has been studied and recording of nerve signals has been attempted by inserting sieve electrodes to be curved into nerve fibers and applying electric stimuli thereto (Anup et.al., Design, in vitro and in vivo assessment of a multi-channel sieve electrode with integrated multiplexer, J. Neural Eng. 3 (2006) 114-24) A total diameter of the sieve is the same as that of a rat sciatic nerve (1.5 mm), and 571 holes having a diameter of 40 μm are disposed therein at 70 μm intervals. In addition, ring-shaped electrodes cover 27 holes and their area is 2200 μm2.
In the case of the first related art described above, there is a problem that noise of the MOSFET device is high and thus only a tendency of electric signals can be measured. Further, in the case of the second related art described above, there is a problem that brain stems or nerve cells are killed when electrodes are inserted. Further, when the sieve electrodes of third related art described above are inserted, cross-talk between the electrodes is generated, and thus there is a problem that the electric signals are not accurately detected.